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Journal of Radioanalytical and Nuclear Chemistry
Authors: S. Ballestra, G. Barci, E. Holm, J. Lopez, and J. Gastaud

Abstract  

This paper describes a radiochemical method for the determination of99Tc in large volumes of rain, river and seawater. The procedure is based on the reduction of technetium to the +4 oxidation state with potassium disulfite in a slightly acidic medium, followed by iron hydroxide precipitation. After oxidation to the +7 oxidation state, the technetium fraction is purified with iron hydroxide and calcium carbonate precipitations. Technetium (+7) is extracted with TBP (xylene) in 3M H2SO4, back extracted in 2M NaOH or ammonia, and the electrodeposition is made in 2M NaOH or H2SO4/NH4OH medium at pH 5–6. The radiochemical yield is determined by gamma counting of the 140 keV gamma ray from99Tcm.99Tc is counted on an anti-coincidence shielded GM-gas flow counter. The purity of the99Tc plated samples is checked by alpha and beta spectrometry using surface barrier detectors and by gamma spectrometry on Ge(HP) detector. The radiochemical yield of 50–150 l water samples is around 20–60%.

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Abstract  

The development of radioanalytical methods for low level radionuclides in marine environmental samples is presented. In particular, emphasis is placed on the introduction of extraction chromatography (EC) as a tool for improving the quality of results as well as reducing the analysis time. However, the advantageous application of EC often depends on the effective use of suitable preconcentration techniques, such as co-precipitation, to reduce the amount of matrix components which accompany the analytes of interest. On-going investigations in this field relevant to the determination of environmental levels of actinides, 137Cs and 90Sr are discussed.

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Abstract  

Analysis of plutonium isotopes by Semiconductor Alpha Spectrometry (SAS), ICP-sector field mass spectrometry (ICP-MS) and Accelerator Mass Spectrometry (AMS) was carried out in seawater samples collected from the Northeast Atlantic Ocean (nuclear waste dumping sites) and Northwest Pacific Ocean. No particularly elevated levels of the atom ratios of 240Pu/239Pu compared to global fallout ratio (0.18) were found in the Northeast Atlantic Ocean seawater samples. The higher levels of atom ratios of 240Pu/239Pu were found in the Northwest Pacific Ocean. This is mainly due to contribution from the local fallout from nuclear weapon tests carried out at the Pacific Proving Grounds at the Marshall Islands.

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Abstract  

241Pu was measured in reference materials and marine samples using a novel method based on rare earth fluoride co-precipitation followed by liquid scintillation spectrometry (LSS). Disc sources used for -spectrometry of 238Pu and 239+240Pu were leached with concentrated nitric acid before neodymium fluoride co-precipitation to scavenge plutonium in the lower oxidation states was carried out. After the determination of the chemical recovery by -spectrometry, the precipitate was recovered in a H3BO3/HNO3 based dissolver and mixed with Packard Insta-GelÒ Plus cocktail before LSS. Reasonable agreement has been obtained between the results obtained using this methods and the data obtained by direct disc analysis by LSS and ICP-MS. The 241Pu/239+240Pu ratios were coherent with the expected origin of the Pu contaminant in the marine environment showing the validity of the method.

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Summary  

New, quantitative methods for the determination of actinides have been developed for application to marine environmental samples (e.g., sediment and fish). The procedures include aggressive dissolution, separation by anion-exchange resin, separation and purification by extraction chromatography (e.g., TRU, TEVA and UTEVA resins) with measurement of the radionuclides by semiconductor alpha-spectrometry (SAS). Anion-exchange has proved to be a strong tool to treat large volume samples, and extraction chromatography shows an excellent selectivity and reduction of the amounts of acids. The results of the analysis of uranium, thorium, plutonium and americium isotopes by this method in marine samples (IAEA-384, -385 and -414) provided excellent agreement with the recommended values with good chemical recoveries.

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Summary  

A procedure is described to extend the current radiochemical method of seawater analysis for Pu and Am including Np. Short-lived 239Np tracer was prepared by separation from its 243Am parent. Irish Sea Water reference material (IAEA-381) containing known concentrations of 237Np, Pu isotopes and 241Am was used to test the procedure for small water volumes. Inductively-coupled plasma mass spectrometry (ICP-MS) was used in addition to alpha spectrometry for measurement of 237Np in the purified final Np fractions.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Pham, M. Betti, P. Povinec, V. Alfimov, D. Biddulph, J. Gastaud, W. Kieser, J. López Gutiérrez, G. Possnert, J. Sanchez-Cabeza, and T. Suzuki

Abstract  

A certified reference material designed for the determination of 129I in seawater, IAEA-418 (Mediterranean Sea water) is described and the results of certification are presented. The median of 129I concentration with 95% confidence interval was chosen as the most reliable estimates of the true value. The median, given as the certified value, is 2.28 × 108 atom L−1 (95% confidence interval is (2.16–2.73) 108 atom L−1), or 3.19 × 10−7 Bq L−1 (95% confidence interval is (3.02–3.82) × 10−7 Bq L−1). The material is intended to be used for standardization procedures applied in accelerator mass spectrometric laboratories. It is available in 1 L units and may be ordered via IAEA web side (www.iaea.org).

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Journal of Radioanalytical and Nuclear Chemistry
Authors: S. Lee, J. Gastaud, J. La Rosa, L. Kwong, P. Povinec, E. Wyse, L. Fifield, P. Hausladen, L. Di Tada, and G. Santos

Abstract  

IAEA reference materials (radionuclides in the marine environment) collected in areas affected by nuclear reprocessing plants and nuclear weapons tests have been analysed by semiconductor alpha-spectrometry (SAS), liquid scintillation spectrometry (LSS) and mass spectrometric techniques (high resolution ICP-MS and AMS) with the aim of developing analytical procedures and to study the geochemical behavior of plutonium in the marine environment. The Pu results obtained by SAS, ICP-MS and AMS were in reasonably good agreement (R 2 = 0.99). The mean atom ratios of 240Pu/239Pu in IAEA reference materials, IAEA-134, 135 and 381 were (0.212±0.010), (0.211±0.004) and (0.242±0.004), respectively. IAEA-384 (Fangataufa Lagoon Sediment) gave a 240Pu/239Pu mean atom ratio of 0.051±0.001. The results of 241Pu obtained by ICP-MS and LSS also show reasonable agreement (R 2 = 0.91). Pu isotopic signatures were useful in tracing Pu origin and in interpreting biogeochemical processes involving Pu in the marine environment.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: P. Povinec, M. Pham, J. Sanchez-Cabeza, G. Barci-Funel, R. Bojanowski, T. Boshkova, W. Burnett, F. Carvalho, B. Chapeyron, I. Cunha, H. Dahlgaard, N. Galabov, L. Fifield, J. Gastaud, J. Geering, I. Gomez, N. Green, T. Hamilton, F. Ibanez, M. Ibn Majah, M. John, G. Kanisch, T. Kenna, M. Kloster, M. Korun, L. Liong Wee Kwong, J. La Rosa, S. Lee, I. Levy-Palomo, M. Malatova, Y. Maruo, P. Mitchell, I. Murciano, R. Nelson, A. Nouredine, J. Oh, B. Oregioni, G. Le Petit, H. Pettersson, A. Reineking, P. Smedley, A. Suckow, T. van der Struijs, P. Voors, K. Yoshimizu, and E. Wyse

Abstract  

A reference material designed for the determination of anthropogenic and natural radionuclides in sediment, IAEA-384 (Fangataufa Lagoon sediment), is described and the results of certification are presented. The material has been certified for 8 radionuclides (40K, 60Co, 155Eu, 230Th, 238U, 238Pu, 239+240Pu and 241Am). Information values are given for 12 radionuclides (90Sr, 137Cs, 210Pb (210Po), 226Ra, 228Ra, 232Th, 234U, 235U, 239Pu, 240Pu and 241Pu). Less reported radionuclides include 228Th, 236U, 239Np and 242Pu. The reference material may be used for quality management of radioanalytical laboratories engaged in the analysis of radionuclides in the environment, as well as for the development and validation of analytical methods and for training purposes. The material is available from IAEA in 100 g units.

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